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View Poll Results: When should a torque plate be used when boring a Pontiac engine?
EVERY single build no matter what. 31 88.57%
400 HP 1 2.86%
500 HP 1 2.86%
600 HP or more 2 5.71%
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  #1  
Old 04-12-2020, 03:03 PM
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Default When to use a torque plate when boring an engine

When should a torque plate be used when boring a Pontiac engine?

I was talking with my machinist about an upcoming engine build and we got on to the topic of torque plates and when one is needed. Since I'm his only Pontiac customer, I would have to buy one for him and he will do the first couple of bore jobs in trade.

I know that it would most likely be better to use one on every build, but at what performance level does it become necessary?

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Old 04-12-2020, 03:28 PM
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Subscribing... my last build was supposed to have been torque plated, but I found out later it was not (Bill found this out when balancing a new rotating assembly for me). Since the bores were good, we left it alone, installed the new assembly and has been running like a champ ever since putting out ~600hp to the crank.

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Old 04-12-2020, 03:36 PM
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Boring with a torque plate CAN be a good idea; honing with a torque plate is a requirement.

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Old 04-12-2020, 04:32 PM
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ALWAYS as far as I'm concerned.

If you've seen one finish honed without, and then took it back and had it finish honed with a torque plate, it's a real eye opener when you see how out of round the cylinders are and how the first past doesn't even touch large portions of the cylinders at all.

Ran into this with a 455 I recently did, which was just redone by another shop. Paul torque plate honed it and the first pass was just absolutely horrible looking. Had to take another .002 to .003" off just to get the cylinders as best as possible without the need for new pistons, but there were still small areas the hone didn't touch. It became apparent right away the first rebuild was not torque plate honed.

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Old 04-12-2020, 06:39 PM
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I bore without a plate and ALWAYS hone with a plate. I leave .005-.007" for honing depending on the job. My boring mill makes using a plate very difficult and not really necessary if you leave enough material to hone. Also, one less operation which would save the customer about $100.00.

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Old 04-12-2020, 08:01 PM
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When you can afford it along with a place within a reasonable distance that can do it proper

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Old 04-12-2020, 08:09 PM
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Years ago, a guy brought me an engine that only had a few hundred miles on it. It was overheating and just not running well.

The bores were in spec for the pistons, but we decided to add new rings and re-hone. The shop used a plate when honing it. There were four VERY obvious oblong circular areas where the hone did not touch, where the cylinder wall was pulled outward by the bolts used on the plate.

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Old 04-12-2020, 10:51 PM
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Quote:
Originally Posted by Lee View Post
Years ago, a guy brought me an engine that only had a few hundred miles on it. It was overheating and just not running well.

The bores were in spec for the pistons, but we decided to add new rings and re-hone. The shop used a plate when honing it. There were four VERY obvious oblong circular areas where the hone did not touch, where the cylinder wall was pulled outward by the bolts used on the plate.
So you re-honed without a plate?

You proved how much the cylinders move around when the bolts are tightened. The cylinders were probably round in-use, and now they won't be.

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Old 04-12-2020, 11:54 PM
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Quote:
Originally Posted by Schurkey View Post
So you re-honed without a plate?
Believe Lee meant "The shop used a plate when REhoning it"?
Or at least that's the way how I read it. HTH.

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Old 04-13-2020, 01:20 AM
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Thanks for that. I guess I misunderstood what order things were happening in.

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Old 04-13-2020, 04:29 AM
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Pontiac distort .004 right under each head bolt about 1/2". I had long conversations with Dan Whittmore on this. He told me you not only need to hone it with a tq plate you need to bore it with one "if you want your bore to be ROUND". That is a direct quote. The guy was anal about such things.
Its not like a sbc where you can bore them .004 under without and hone with and you are fine. Some shops can not bore and hone with a plate because of their equipment. My last 400 was done in a shop where he could not do as I wanted. So he bored it .010 under and ridged honed it to spec (.006 clearance since it is hard blocked) .
I paid Dan extra to do one of his tq plate bore and hone jobs. He passed before he got it done.
So when I got the block and had to have it finished by a local guy he checked out everything with a fine tooth comb. Dan fit the billet splayed caps, got that part done. When the guy inspected it he said he was impressed with the caps. Said the main bores were dead on the nuts. Asked who did it and I said some guy back east. You can see remnants of the factory main hone barely viable, just kissed the block.
I expect a very good ring seal on this engine. Dan hard blocked it and used a tq plate for the cure, it matters with that guy. It cured for 3-4 MONTHS on each side with the same type gasket I am using, 1016.

OPs original question ? I say all tq plate the time. I mean, on a typical daily driver why would it matter. But Pontiac these days are anything but daily drivers. They are our "babies". Make it run sweet, crisp.

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Old 04-13-2020, 01:37 PM
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Thanks for the replies.

Where can I buy a torque plate or find the specs to have one made?

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Old 04-13-2020, 02:46 PM
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Quote:
Originally Posted by 242177P View Post
Believe Lee meant "The shop used a plate when REhoning it"?
Or at least that's the way how I read it. HTH.

Correct, thank you!

1st shop honed w/o a plate, motor was run for a few hundred miles - long enough to smooth out the cross-hatch and add some vertical lines to the bore.

2nd shop RE-honed WITH torque plate. The previous "vertical" marks were obliterated by the new cross-hatch - EXCEPT around the areas where the bolts ended, where there were circular areas that still had the vertical marks.

I wish I had a photo.

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'67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust

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Old 04-13-2020, 05:16 PM
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There is a Tampa chapter of the Pontiac Oakland GMC club. Worth a try to contact them and see if a member knows of where you might borrow one.


.

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Old 04-13-2020, 05:29 PM
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I don't know where Ken Keefer lives. I here he is working out of his house. he is on face book. Maybe you could rent his plate???

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Old 04-13-2020, 05:32 PM
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Quote:
Originally Posted by Speargun View Post
Thanks for the replies.

Where can I buy a torque plate or find the specs to have one made?
BHJ and Sunnen are the two suppliers I use, but their are others as well. IMO, the BHJ plates are a little nicer.

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Old 04-13-2020, 05:32 PM
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Quote:
Originally Posted by Speargun View Post
Thanks for the replies.

Where can I buy a torque plate or find the specs to have one made?
Years ago I called the place where machine shops rent their tq plates and asked if they had one. They said no but I asked nicely, well more like pleaded with them to get one for our Pontiacs. And they did ! Local machine shop owner said he did not have that kind of pull. But I got lucky and the guy must have been in a good mood.
Give it a try, all they can say is no. Sometimes phone calls do work.
There is a place that sells aluminum tq plates for engines for 360$, not bad. Somewhere there is a link to it around here.
Reminder, it does make a small difference in bore distortion with type of head, iron or aluminum. Same thing with tq plates.
The 461 I just did used a steel plate but will get aluminum heads. The 540 planed build I will make sure to get a aluminum tq plate.
It just would have been a major pain to drag up or buy a aluminum one. I should have just bought the one for 360$ and been done with it.
Remember, it does matter what kind of head gasket is under the tq plate when machined. You need to use the same kind of gasket in the engine itself.

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Old 04-13-2020, 05:39 PM
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All of the ones I bought except for the 455 Buick unit, came "used" from eBay. After years of watching, I never saw a Big-Block Buick plate for sale. I paid, on average, about $200 for the used ones plus shipping. The Buick was ~$400 new, plus shipping.

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Old 04-13-2020, 05:48 PM
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Quote:
Originally Posted by Speargun View Post
Thanks for the replies.

Where can I buy a torque plate or find the specs to have one made?
BHJ is the only supplier of Pontiac torque plates I'm aware of unless you want to produce your own. If you have access to a WaterJet and have a head gasket it shouldn't be too difficult.

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Old 04-13-2020, 05:50 PM
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Quote:
Originally Posted by mgarblik View Post
BHJ and Sunnen are the two suppliers I use, but their are others as well. IMO, the BHJ plates are a little nicer.
Mike, I wasn't aware that Sunnen made torque plates for Pontiacs. We made our own, but we had access to TONS of 1 inch steel plate and a tool and die department.

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